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Thread: My experience with my 4L80E on T42 swap with

  1. #1
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    Default My experience with my 4L80E on T42 swap with Frost Harness

    Hope this helps someone in the future ... after a fresh rebuild on the trans and converter, I wanted to make sure everything was GOOD before we did any damage ... I'll go through all the steps we followed and discoveries etc. I'm not an expert at any of this but I've learned a lot. If you wanna get down to the troubleshooting, just go down to the ******

    Truck is a 2009 Silverado LY5 ... E38 ECM and T42 TCM, running a 4L80E swap on 4L60E tune with an early Frost conversion harness with the external PRNDL switch harness pinned into it as the 2009 4L60E didn't have it on the side of the trans and did it internal. It also had an internal ISS that I haven't wired in on the 4L80E as that's not really required.

    Right after putting my 3200 Stall in, the transmission started overheating and eventually started making metallic noises and so we pulled the trans and sent it out to be rebuilt and the converter was also sent out to be freshened up. Turns out some of the trans connector pins were bent and also wan't making full contact as the plug had been pushed into the trans. I'm hitting my head on the wall for not noticing this during install. The clutches were all burned out and the converter lockup clutch was bare metal ... it wasn't pretty. After a flush of the cooling lines, everything was re-installed and fresh fluid filled.

    Drove her around and although things seemed to work fine but we noticed the temps started climbing again. Came back to the ship and put Original tune in with only a few numbers like gear ratios etc. changed and ISS codes turned off. Everything seemed to work fine and temps stayed normal ... so something I did when copying all the 4L80E tables from a Van may have affected it? keep reading.

    Drove her home and had a check engine light turn on and the TCC never locked up ... also temps started rising a little bit (210F) before I got home. This was pissing me off...

    Next morning ... pretty cold out ... drove the truck and noticed no TCC lockup on a trip to Dentist. But after, it seemed to lock up on my way to the transmission shop; he was gonna ride with me with his scanner when the weather was better than yesterday's rain. He read the 2 codes as "low idle" and "brake pedal switch issue" < not exactly what it said but you get the point.

    ****** TROUBLESHOOTING AND DISCOVERIES ******

    He noticed that as soon as I took off, the TCC PWM value would go directly to 99% and stay there; but the TCC On/Off signal was still OFF. Now this 99% value wasn't surprising as we had the Min PWM tables maxed as we wanted to eliminate PWM. BUT, the converter never locked up or made any effort. It would have been messy if it did too, as it maxed out immediately as it detected any movement. When the Lockup signal turned on, the TCC locked up as expected. He was worried about the TCC PWM signal status not doing anything and advised we try to figure out what the heck the TCM was doing.

    Speaking to another tuner in the area who's done these swaps, he stated that the PWM signal is probably internal not being sent to trans until certain parameters are set? Well the trans shop wasn't buying that as he said that's the output and not an internal value.

    ****** FROST HARNESS ******

    Brought the truck home and took out the Frost Harness to check if the relays were bad or anything of that sort. The relay that swapped Solenoid B status was fine and left alone.
    Tracing TCC/PWM wires between the ends and the relays, I noticed that the PWM signal goes through the N/O terminal of the relay on its way to the transmission (when not active, a 10K ohm resister is branched off to avoid the MIL). This shows why the PWM signal never did anything until the on/off signal was set. But, this would have also saved us as we maxed out the Min PWM table ... having the PWM signal maxing out off of idle would have created a mess of things.

    In my situation, since I didn't need PWM anymore, I ran the TCC On/Off wire directly to the PWM input signal of the trans (just as everyone else does). Left the PWM signal connected to resister to avoid any MIL issues.

    Here's a bad drawing with my understanding of the controls and how I think it should've been. Although thinking my way is will make it act like there's no PWM when coming to a stop as I've noticed it stays locked till the MPH is pretty low (helps braking though!) I'd have thought the Relay activation would have sent ground to the PWM and run the TCM PWM signal when not as shown. I'm open to your thoughts.

    Click image for larger version. 

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    ****** BRAKE PEDAL SWITCH ******

    Also read that the brake pedal switch MIL we saw may cause TCC and Cruise control issues. Was gonna buy a new one, but decided to take the existing one off and clean the connections in case they were dirty.

    A combination of these worked as I now have very positive TCC lockup that I can tune and have no doubt that PWM can cause any issues with burning up my clutches etc. if not tuned right.

    ****** LESSONS LEARNED ******

    Having the Harness as it was requires running full PWM control, you cannot max out the Min PWM table as it will mess up drive ability in this application.
    Be careful when connecting the Trans harness connector.
    The brake switch can affect a whole bunch of shit!
    Last edited by Mean Green Z28; December 8th, 2016 at 03:02 PM. Reason: clarified some information

  2. #2
    Joe (Moderator) joecar's Avatar
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    Thanks for posting, this is very helpful to various people


    Quote Originally Posted by Mean Green Z28 View Post
    ****** TROUBLESHOOTING AND DISCOVERIES ******

    He noticed that as soon as I took off, the TCC PWM value would go directly to 99% and stay there; but the TCC On/Off signal was still OFF. Now this 99% value wasn't surprising as we had the Min PWM tables maxed as we wanted to eliminate PWM. BUT, the converter never locked up or made any effort. It would have been messy if it did too, as it maxed out immediately as it detected any movement. When the Lockup signal turned on, the TCC locked up as expected. He was worried about the TCC PWM signal status not doing anything and advised we try to figure out what the heck the TCM was doing.

    Speaking to another tuner in the area who's done these swaps, he stated that the PWM signal is probably internal not being sent to trans until certain parameters are set? Well the trans shop wasn't buying that as he said that's the output and not an internal value.
    Yes, correct, TCC is applied only when TCC ON/OFF is ON and TCC PWM is above 80% (or so).


    ****** FROST HARNESS ******

    Brought the truck home and took out the Frost Harness to check if the relays were bad or anything of that sort. The relay that swapped Solenoid B status was fine and left alone.
    Tracing TCC/PWM wires between the ends and the relays, I noticed that the PWM signal goes through a the N/O terminal of the relay on its way to the transmission. This shows why the PWM signal never did anything until the on/off signal was set. But, this would have also saves us as we maxed out the Min PWM table ... having the PWM signal maxing out off of idle would have created a mess of things.

    In my situation, since I didn't need PWM anymore, I ran the TCC On/Off wire directly to the PWM input signal of the trans. Left the PWM signal connected to resister to avoid any MIL issues.
    Yes, I would drive the TCC from the TCC ON/OFF signal as you did
    Last edited by joecar; December 8th, 2016 at 10:42 AM.

  3. #3
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by Mean Green Z28 View Post
    ...

    Here's a bad drawing with my understanding of the controls and how I think it should've been. Although thinking my way is will make it act like there's no PWM when coming to a stop as I've noticed it stays locked till the MPH is pretty low (helps braking though!) I'd have thought the Relay activation would have sent ground to the PWM and run the TCM PWM signal when not as shown. I'm open to your thoughts.

    Click image for larger version. 

Name:	2016-12-08 16.09.34.jpg 
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Size:	597.4 KB 
ID:	20537
    Your diagram (rhs) does not show the TCC ON/OFF signal driving the TCC...?

    ****** BRAKE PEDAL SWITCH ******

    Also read that the brake pedal switch MIL we saw may cause TCC and Cruise control issues. Was gonna buy a new one, but decided to take the existing one off and clean the connections in case they were dirty.

    A combination of these worked as I now have very positive TCC lockup that I can tune and have no doubt that PWM can cause any issues with burning up my clutches etc. if not tuned right.
    Yes, correct, brake switch input is important for TCC control.

    ****** LESSONS LEARNED ******

    Having the Harness as it was requires running full PWM control, you cannot max out the Min PWM table as it will mess up drive ability in this application.
    Be careful when connecting the Trans harness connector.
    The brake switch can affect a whole bunch of shit!
    I lube the connector pins with TransGel/vaseline (and I'm very paranoid about bend pins).
    Last edited by joecar; December 8th, 2016 at 10:43 AM.

  4. #4
    Joe (Moderator) joecar's Avatar
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    See posts #12 and #16 here: 4L80E-Reference-Material~post#12


    Quote Originally Posted by joecar View Post
    To drive a 4L80E transmission from a 4L60E segment:
    - discard the 3-2 control solenoid signal.
    - drive the 4L80E 2-3 shift solenoid by using a relay to invert the 4L60E 2-3 shift solenoid signal;
    - drive the 4L80E TCC PWM solenoid from the 4L60E TCC ON/OFF signal (discard the 4L60E TCC PWM signal), or see Alternative below;

    Alternative (see posts #27 and #29 here, thanks GNXClone/Mike):
    use the 4L60E TCC ON/OFF signal to control a relay which gates the 4L60E TCC PWM signal to the 4L80E TCC PWM solenoid:




    TCC PWM warning:
    the 4L60E may on occasion park the TCC PWM signal at 90% while the TCC is off,
    this is the reason you don't want to drive the 4L80E TCC PWM solenoid solenoid directly from the 4L60E TCC PWM signal signal
    (i.e. use a relay as Alternative says, or use the ON/OFF signal).

    Note:
    The F-car 4L60E segments keep the TCC locked on closed throttle decel (until vss goes below the unlock curve).
    The Truck 4L80E segments (there are no 4L80E car segments) unlock the TCC on closed throttle.

    To invert the 2-3 shift signal:

    relay is connected as follows:
    - the relay control coil is connected between 12V and the 2-3 shift solenoid signal from the PCM,
    - the NC (off) relay contact goes to GND,
    - the NO (on) relay contact goes to 12V,
    - the swinging/gated contact goes to the 2-3 shift solenoid signal in the trans,

    i.e. so when the PCM has the signal off (12V) the relay turns it on (GND), and vice-versa.


    Also:
    need to provide wiring to input 4L80E ISS signal into PCM.
    Quote Originally Posted by joecar View Post
    4L60E: has TCC PWM and TCC On/Off.
    4L80E: has TCC PWM only.

    That is just how they were designed.


    4L60E operation:
    PCM ramps up TCC PWM and enables TCC On/Off to lock the TCC.
    While TCC is unlocked, PCM may ramp TCC PWM up to 90% just for the heck of it (maybe to clean the hydraulic circuit).

    4L80E operation:
    PCM ramps up TCC PWM to lock the TCC.

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    Quote Originally Posted by joecar View Post
    Your diagram (rhs) does not show the TCC ON/OFF signal driving the TCC...?
    I'm assuming; since the PWM and On/Off signals are ( - ), I ground the signal to the trans and activate full lockup. The Common goes to trans and either PWM or Ground goes to trans depending on TCC on/off signal. With relay off, we get the PWM signal going through N/O terminal to Common (trans). TCC on off signal still activates relay and sends ground signal like on/off does.

    Does that make sense?

    The reasoning for my schematic is because I've read your explanation that the TCM may ramp down PWM after TCC On/Off signal is active .. this eliminates the 4L80E TCC also unlocking or atleast getting a lower PWM signal when locked.

    The 4L60E may have been able to deal with a ramp down of PWM with On signal but the 4L80E will release.
    Sent from my SAMSUNG-SM-G900A using Tapatalk
    Last edited by Mean Green Z28; December 8th, 2016 at 02:18 PM.

  6. #6
    Joe (Moderator) joecar's Avatar
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    Remove the relay and connect TCC ON/OFF directly to 4L80E TCC PWM


    ( and connect the TCC PWM to a 10K resistor going to +power (to keep the DTC from tripping) )

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    Quote Originally Posted by joecar View Post
    Remove the relay and connect TCC ON/OFF directly to 4L80E TCC PWM


    ( and connect the TCC PWM to a 10K resistor going to +power (to keep the DTC from tripping) )
    That's what I did ... the pic was just me thinking out aloud; if someone were to want to use PWM and still have full lockup using the On/Off signal ... or maybe I wanted to go back and test out my theory using PWM and Lockup functions.

    Thanks for all your help and guides, I've learned a LOT from reading them

    Sent from my SAMSUNG-SM-G900A using Tapatalk
    Last edited by Mean Green Z28; December 8th, 2016 at 03:05 PM.

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    So getting back to this, anyone think my schematic would work to keep PWM active until full lockup using the on/off. Just not sure how those signals are handled during unlock and coasting.

    Ofcourse we've always done full lockup instead of PWM in the swaps as we know the 4L80E will handle it but this is just in case someone still wanted some resemblance to a smooth factory like lockup experience.

    Sent from my SAMSUNG-SM-G900A using Tapatalk
    Last edited by Mean Green Z28; December 13th, 2016 at 07:54 AM.

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